RadD from <i>Fusobacterium nucleatum</i> engages NKp46 to promote antitumor cytotoxicity.

Abstract

<i>Fusobacterium nucleatum</i>, a gram-negative bacterium implicated in periodontal disease, contributes to tumor progression in various cancers. Whether the presence of <i>F. nucleatum</i> inhibits tumor progression of some cancers is largely unknown. Here, we identify an interaction between <i>F. nucleatum</i> and the natural killer (NK) cell receptor NKp46. Analysis of TCGA datasets revealed that the co-occurrence of <i>F. nucleatum</i> and high NKp46 expression correlates with improved survival in head and neck cancers but not in colorectal cancers. Using binding assays, we demonstrate that both human NKp46 and its murine ortholog, Ncr1, directly recognize the fusobacterial adhesin RadD. Genetic deletion of <i>radD</i> or blockade of NKp46 significantly impaired NK cell-mediated cytotoxicity in vitro and promoted tumor-cell growth. In vivo, infection with <i>F. nucleatum</i> accelerated tumor progression, with an exacerbated effect observed in the absence of RadD or NKp46. These findings highlight RadD as a critical ligand for NKp46 and establish the NKp46-RadD axis as a key interface in host-microbe-tumor interactions, offering a novel target for immunotherapeutic intervention in cancer influenced by microbial factors.